Hello, When I tried to stop a sql server service on a server, it also pops up a message saying it will also stop sql agent service and arcGIS service (sde), so it seems there is a dependency there,how to add or remove a dependency to sql server service?

To remove a depenancy you need to go to the following registry entry: HKLM\SYSTEM\CurrentControlSet\services\<service>. There you find a REG_MULTI_SZ key named DependOnService where you can remove any services your service depends on

While you can, I don't recommend that you should. If the service has been set as dependant on SQL Server, there's probably a good reason. Removing that dependency may cause unexpected behaviour. At least speak to the vendor before you go and change the configuration of their app's services.

ARCGIS or ARCSDE may use either an oracle or sql server RDBMS, it wouldn't be my preference to install the GIS system on the database server as these systems can be extremely intensive. A multi tiered approach is much better to guarantee performance.

Check with ESRI the vendor if the depedency is something they set, from my experience it's not but better to check anyway.